The radio access technology standards such as LTE (Long Term Evolution)/LTE-A (LTE-Advanced) are built based on MIMO (Multiple-Input Multiple-Output)+OFDM (Orthogonal Frequency Division Multiplexing) technology. The MIMO technology utilizes the spatial freedom that multi-antenna systems can achieve to improve peak rate and system spectrum utilization.
The dimensions of MIMO technology continue to expand during the development of standardization. In LTE Rel-8, up to 4 layers of MIMO transmission can be supported. The RC-MIMO (Multi-User MIMO) technology, TM (Transmission Mode)-8 MU-MIMO transmission can support up to four downlink data layers. The transmission capability of SU-MIMO (Single-User MIMO) is extended to a maximum of 8 data layers in Rel-10.
The industry is further promoting the MIMO technology to be three-dimensional and large-scale. At present, 3GPP has completed research projects on 3D channel modeling, and is conducting research and standardization of eFD-MIMO (evolved Full-Dimension MIMO) and NR MIMO (New Radio MIMO). It is foreseeable that in the future 5G mobile communication system, a larger scale, more antenna port MIMO technology will be introduced.
Massive (large-scale) MIMO technology uses large-scale antenna arrays to greatly increase system bandwidth utilization and support a larger number of access users. Therefore, major research organizations regard massive MIMO technology as one of the most promising physical layer technologies in the next generation of mobile communication systems.
In the massive MIMO technology, if an all-digital array is used, a maximum spatial resolution and optimal MU-MIMO performance may be achieved, but this structure requires a large number of AD/DA (analog-to-digital/digital-to-analog) conversion devices and a large number of complete RF-baseband processing channels, whether it is equipment cost or baseband processing complexity, will be a huge burden.
In order to avoid the above implementation cost and equipment complexity, digital-analog hybrid beamforming technology emerges, which is based on the traditional digital domain beamforming, adding a first-order beam assignment to the RF signal near the front end of the antenna system. Analog shaping enables a relatively coarse match between the transmitted signal and the channel in a relatively simple manner. The dimension of the equivalent channel formed after the analog shaping is smaller than the actual number of antennas, so the required AD/DA conversion device, the number of digital channels, and the corresponding baseband processing complexity can be greatly reduced. The residual interference of the analog shaped portion can be processed again in the digital domain to ensure the quality of the MU-MIMO transmission. Compared with full digital shaping, digital-analog hybrid beamforming is a compromise between performance and complexity. It has a high practical prospect in systems with high bandwidth and large number of antennas.
In the current LTE system, the UE (User Equipment, or referred to as terminal) is allowed to have different product costs and applications. Then, the UE can report its own access network capability, and the network side can provide the network. A better service that matches the capabilities of the UE. That is to say, when the network side makes various event decisions or executes various algorithms, it needs to know the capabilities of the UE to make the most appropriate decision.
In the UE EUTRA capability (the evolved UMTS land-based radio access capability of the UE), the following message content is included:
a. access layer release: set to the 3GPP version number supported by the UE;
b. UE category (category);
c. PDCH (Packet Data Channel) parameters: describe the ROHC profile (Robust Header Compression Profile) combination supported by the UE, and the maximum number of header compression context sessions supported by the UE, etc.;
d. Physical layer parameters: whether the UE supports antenna selection, whether the UE supports UE specific RS (specific reference signal) for downlink support under FDD (frequency division duplex);
e. RF (Radio Frequency) parameters: indicate the EUTRA band that the UE can support, whether the UE supports half-duplex or full-duplex, etc.
f. measurement parameters: including whether or not measurement gaps (measurement gaps), etc.;
g. Feature group indicators (FGI): Supports the execution and testing of all functions when the specific indicator is “True”, otherwise it is “false”, setting all unsupported functions to “false”.
h. InterRAT (different system cell handover) parameters: refers to the UE's ability to support different systems, which is an important basis for the network side to determine whether the UE can interoperate.
In the UE EUTRA capability, the parameters of the UE category define the uplink and downlink capabilities of the UE, including:
The downlink physical layer parameter value series includes: a total number of bits of the DL-SCH (downlink shared channel) transport block received in one TTI (transmission time interval), and a DL-SCH transport block received in one TTI The maximum number of bits, the total number of soft channel bits, the maximum number of spatial multiplexing layers supported by the downlink, and the like.
The uplink physical layer parameter value series includes: the total maximum number of bits of the UL-SCH (uplink shared channel) transport block received in one TTI, the maximum number of bits included in one UL-SCH transport block received in one TTI, and the uplink whether to support 64QAM (phase quadrature amplitude modulation) and the like.
L2 buffer size, etc.
It should be noted that when the capability reporting of the UE is the first ATTACH (attachment) or TAU (tracking area update) of the UE, the UE actively reports its own capability, which belongs to the NAS (non-access stratum) process. In the RRC (Radio Resource Control) specification at the network side also has a UE capability query process to acquire and deliver UE capabilities, including:
1) First, the UE boots up and establishes synchronization and access with the network, namely:
 The UE sends an RA preamble (random access preamble) to the base station;
 The base station sends an RA response (random access response) to the UE;
 The UE sends an RRC Connection Request to the base station;
 The base station sends an RRC Connection Setup to the UE;
 The UE sends an RRC Connection Setup Complete to the base station to complete the establishment of the RRC connection.
2) The base station sends an Initial UE message to the MME (Mobility Management Entity), including: Attach Request, PDN connectivity request message, and the like.
3) The MME sends an Initial context setup request to the base station, including: Attach Accept, Activate default EPS bearer context request, to complete the connection of S1. By completing these procedures, it is indicated that the establishment of the NAS signaling connection (non-access stratum signaling connection) is completed.
4) If the UE Radio Capability IE (radio capability information element) is carried in the above message Initial context setup request, the base station does not send a UE Capability Enquiry message to the UE. Otherwise, the base station will initiate a UE capability enquiry procedure, which is often seen in the first network access, that is:
 The base station sends the UE Capability Enquiry to the UE;
 The UE sends UE Capability Information to the base station.
The base station then sends a UE Capability info Indication to the MME. That is, the UE reports its own wireless capability information, and the base station then reports the wireless capability information of the UE to the core network.
It can be seen from the description that when mass MIMO uses digital analog hybrid beamforming technology, the corresponding antenna array structure will be designed. For example, adding a panel, each panel can be connected to the corresponding baseband unit and sent to each. The analog beam and the array of panels can be digitally shaped to achieve coverage of a specific geographic area.
In the UE capability design and reporting in the related art, if there is not such antenna array structure information message, then in the subsequent use procedure, it is impossible to provide a more efficient beam management, more precise beam alignment, more optimized multi-user scheduling and multi-data flow transmission to the system when using more antennas for user scheduling and data transmission.